1. Field of the Invention
The present invention relates to an optical sensor system which is for docking of two satellites existing on an orbit with one satellite (which will be referred hereinafter to as a chaser) measuring relative coordinate position/attitude of the other satellite (which will be referred hereinafter to as a target).
2. Description of the Prior Art
In a proposed conventional rendezvous docking optical sensor system, as illustrated in FIGS. 11(a), 11(b) and 12, a light source 3 and image pickup device 4 constituting an optical sensor 1 are mounted on a chaser 2 and a plurality of reflector markers 6 disposed to form a pattern are provided in a target 5. An operation of the conventional optical sensor 1 will be described hereinbelow. First, light is emitted from the chaser 2 toward the target 5. Here, since the chaser 2 does not exactly confirm the coordinate of the target 5, the light is emitted to advance within a diverged visual field including a direction in which it is considered as the target 5 exists. In response to the incidence of the light from the chaser 2, the reflector markers 6 of the target 5 reflect the light. Generally, in the reflector markers 6, there is provided a corner cube whereby the light is effectively reflected toward the light source. The image pickup device 4 of the chaser 2 receives, on its image-formation surface, an image having a deformed pattern configuration of the plurality of reflector markers 6. The deformed state of the pattern configuration of the reflector markers 6, incident on the image pickup device 4, with respect to a pattern obtained when being in opposed to the reflector markers 6 at a docking distance is calculated by a computer 7, thereby detecting the relative coordinate position and attitude. Secondly, a position control section 8 of the chaser 2 is operated so that the detected relative position/attitude becomes a coordinate position/attitude suitable for the docking. With the above-described processes being repeatedly performed, the final docking is effected.
The conventional rendezvous docking optical sensor 1 has the following problem. That is, because of emitting light from the chaser 2, the reflection from the body of the target 5 on which the reflector markers 6 are pasted is incident as the background light, particularly, in the case that a capton which is a heat control material is pasted on the base thereof, since the regular reflected light returns to the chaser 2 due to irregularities on the surface of the capton, a high-grade image processing is required in order to differentiate it from the reflection due to the reflector markers 6. The high-grade image processing requires a CPU of the computer 7 which can perform the processing at a high speed. However, of the actual high-speed processing CPUs, there is no CPU which has a high reliability for use in the space. Thus, it is required to perform the high-grade image processing with a low-speed CPU, thereby causing the processing time to become long. Accordingly, the conventional system which requires a long processing time has a low safety because the satellite detects the relative coordinate position/attitude when in a moving state.